Regina (HRH Sultan of Pahang) v Secretary of State for the Home Department – WLR Daily

“The question of who was a head of state such as to attract state immunity was a matter for the Secretary of State for Foreign and Commonwealth Affairs and not for the court. A certificate issued by the Secretary of State under section 21 of the State Immunity Act 1978 was conclusive evidence of the status of a territory for the purposes of Part I of the 1978 Act. The certificate was the only proper means by which the court could, for the purposes of the common law where it continued to apply, inform itself of a territory’s status and of the identity of the head of state.”